1. Field of the Invention:
The present invention relates generally to the field of fluid-powered actuators, and more particularly to an improved rotary actuator which may be usefully employed in a wrist actuator capable of movement about multiple axes.
2. Description of the Prior Art
A fluid-powered rotary actuator is basically a device for converting pressurized fluid flow into rotational movement of a shaft relative to a body. Many forms of such rotary actuators have been developed heretofore. It is also known that an electrohydraulic servovalve may be used to control movement of the shaft relative to the body.
In recent years, there has been increasing interest in the development of robots for the performance of mechanical acts, such as on automobile assembly lines and the like. Such robots have been designed with degrees of freedom comparable to human joints. The human wrist, for example, is capable of rotational movement about three mutually perpendicular axes, and may be selectively positioned by extension or retraction of the person's arm. The desire to develop satisfactory robots has lead to a concomitant desire to develop actuators simulating human joints.
Earlier efforts at such robots and actuators are shown in the following U.S. Pat. Nos. 3,984,009; 3,739,923; 2,861,701; 4,096,766; 4,062,455, 2,528,464; 3,954,188; 3,543,910; 3,454,169; 2,629,876; 3,605,474; and 2,422,530.